1. Technical Field
The present teachings relate generally to locking differentials for vehicles and, more specifically, to features of a locking differential having preload springs for maintained contact.
2. Description of the Related Art
Locking differentials of the type contemplated by the present teachings are employed as a part of a drive train and generally include a pair of clutch members supported for rotation in a housing. A pair of side gears is splined for rotation to corresponding axle half shafts. A clutch mechanism is interposed between the clutch members and the side gears. A cross pin is operatively mounted for rotation with the housing and is received in a pair of opposed grooves formed on the inwardly facing surfaces of the clutch members. In an event requiring differential rotation between the axle half shafts, such as cornering, the higher speed axle shaft advances its clutch to an over-running condition, decoupling it from the powertrain torque. If the driving terrain provides insufficient traction to activate the over-running feature of the differential, or while driving in a straight line, torque is applied equally to both axle shafts.
While locking differentials of this type have generally worked for their intended purposes, certain disadvantages remain. More specifically, for reasons of noise/vibration/harshness (NVH) and performance, the clutch members must have a pre-load acting on them, forcing maintained contact between a driver shaft or cross pin and clutch members and, in turn, preventing a “contact” noise during relative motion of the cross pin and clutch members during operation of the differential mechanism. The clutch discs need pre-load to generate the resistance to rotate force, allowing the engagement motion of the cross pin on the clutch members. In particular, the clutch members generally need relatively small pre-load for abatement of NVH, but the clutch mechanisms need variability in their pre-load based upon parameters of the corresponding vehicle, and is additionally influenced by the pre-load of the clutch members. Adding pre-load to the clutch members generates additional axial resistance to compression, as defined by the incline angle of the groove geometry. Known designs apply a pre-load to the clutch mechanisms that influence the entire differential mechanism, which is undesired.
Thus, there remains a need in the art for a locking differential that is designed so as to prevent a “contact” noise during relative motion of a cross pin and clutch members during operation of a differential mechanism.